a horizontal speed of 15.8 m/s and a vertical speed 10.0 m/s upward. What is the vertical speed 1.12 s later?

I assume you are referring to a projectile on planet earth with an acceleration due to gravity of 9.8 m/s².

Neglecting air-resistance, the horizontal velocity (speed) does not affect the vertical velocity.

From the initial vertical velocity of u=10 m/s, and g=-9.8 m/s², after t=1.12 seconds, the vertical velocity, v, is given by:

v=u+gt

hint: watch out for the sign of g.